1. Field of the Invention
The present invention relates to the management of stormwater runoff, and more particularly concerns devices which minimize and facilitate sediment maintenance, expand the storage capacity of stormwater management systems, and facilitate the infiltration of stormwater into the surrounding substrate.
2. Description of the Prior Art
Culverts, catch basins, and storm sewers are the common practices for collecting and conveying stormwater runoff. In some instances such water is discharged directly into the nearest available water body despite the potentially adverse environmental effects of such action. In some other instances, stormwater management facilities are constructed to help manage the quantity and quality of the stormwater. Wet or dry retention or detention basins/ponds represent the most common structural approach to stormwater management. Although more environmentally sound than direct discharge into an existing body of water, such stormwater management approaches preclude other uses of the land. This is of particular importance where land values are high and/or space is limited. The open ponds may also be undesirable in locations near airports because of birds attracted by the pond, or in locations where health, liability or aesthetic considerations make them undesirable. Even the use of “dry” detention basins frequently results in the same type of problems associated with wet ponds. Without proper maintenance, dry detention basins frequently transform into wet ponds.
Underground systems have also been developed to help manage stormwater effluent. Such systems include the use of plastic arch-shaped, open bottom stormwater chambers arranged end-to-end in rows. However, all current underground stormwater management systems are limited by the amount of area available for their installation. This is particularly relevant to the plastic stormwater chambers. The largest plastic chamber currently on the market has an arched cross-sectional area of 34 inches high by 60 inches wide and a length of eight and one half feet. The creation of larger chambers is limited by the forming capacity of molding machinery.
In a typical installation of plastic stormwater chambers, elongated hollow plastic chambers are emplaced in the ground to form a leaching field for receiving stormwater and dispensing the water into the surrounding earth. Such chambers have a central cavity for receiving inflow water. An open bottom, and apertures optionally located in the sides of the chambers provide the means whereby the water is allowed to exit the central cavity and disperse into the surrounding earth. The chambers are usually attached endwise to form long rows extending in side-by-side juxtaposition and seated upon a granular substrate such as crushed rock in a multi-row array that constitutes a leaching field. The stormwater is generally conducted to the array of rows by a large diameter manifolded pipe system that runs orthogonally to the rows closely adjacent one extremity thereof.
Examples of stormwater dispensing chambers are disclosed in U.S. Pat. Nos. 5,017,041; 5,156,488; 5,336,017; 5,401,116; 5,441,363; 5,556,231 and 6,361,248.
Stormwater typically carries considerable amounts of suspended particulate material, commonly referred to as Total Suspended Solids (TSS), which eventually settles out as sediment within the stormwater management system. The accumulation of such sediment adversely affects the storage capacity of stormwater management facilities, decreasing their effective life. The effective life of such facilities can be significantly extended with a maintenance program for sediment removal. Such sediment removal can generally be achieved by a vacuuming operation conducted by a suitably equipped truck. In such operation, a tube is extended from the truck through a manhole, through an associated riser pipe, and into the bottom of the chamber. The sediment in the bottom of the chamber is then removed by vacuuming.
Unfortunately, the maintenance of stormwater management systems is often neglected, and typically occurs only when the system fails or sediment accumulates to a point where flooding occurs because of diminished storage capacity of the system. This problem has become so serious that some municipalities have imposed a stormwater maintenance “fee” on property owners to help pay for private-sector stormwater facility maintenance.
Unlike stormwater wet and dry ponds, which are readily observable and accessible, removal of sediment from underground stormwater management facilities has historically been inherently more inconvenient and costly, resulting in resistance to their use by some municipalities. Some types of underground stormwater management facilities even have to be replaced in order to remove accumulated sediment.
patent application Ser. No. 10/330,595, filed Dec. 30, 2002 by the same inventor discloses a sediment-accumulating accessory device which, when deployed beneath a plastic chamber having a top portal, facilitates the accumulation and removal of TSS. It has been found, however, that the installation of such accessory devices is difficult because they tend to be buoyed upwardly when the granular backfill material is poured into surrounding relationship with the accumulating device and associated chamber.
It is accordingly an object of the present invention to improve the sediment handling capacity of an underground stormwater management system.
It is another object of this invention to provide an accumulating accessory device interactive with a plastic stormwater dispensing chamber to increase the sediment handling capacity of an underground stormwater management system comprised of said chambers.
It is a further object of the present invention to provide a plastic stormwater dispensing chamber combined with an accumulating accessory in a manner to facilitate removal of accumulated sediment.
It is yet another object of this invention to provide an accumulating device of the aforesaid nature which resists buoyant upward movement produced by granular backfill material.
It is an additional object of the present invention to provide a combined stormwater dispensing chamber and accumulating accessory of the aforesaid nature of durable, simple construction amenable to low cost fabrication and installation.
These objects and other objects and advantages of the invention will be apparent from the following description.